If you have the BBC computer and can run the software you could try it out to see if it suits your needs.

If you don't have the computer then probably going straight for a retro-fit will be the best alternative.

Emgee

While the hardware of a BBC is well documented its entire way of working with peripherals is different to a PC or clone.

There are a number of different interfaces on a BBC Micro and the first this is to discover which one is used bt the Boxford.

Tube – Used to connect a second processor so the least likely however if the Boxford contains a microprocessor it is possible

1MHz bus – used to connect slower peripherals but has a more direct link to BBC hardware so could be.

User port – a general purpose I/O port

Printer – a cut down Centronics interface that may be similar to the 25pin printer port in your PC

Is this any use?

BBC hardware is well documented onine

The most likely are the user port (20pin) or printer port (26way)

The 1MHz bus is 34 pin and the Tube 40 pin

Edited By Nick Clarke 3 on 04/04/2020 17:37:05

Edited By Nick Clarke 3 on 04/04/2020 17:38:53

Hi Leonard, I think you will find that the interface is unlikely to work directly with Mach 3.

You would need some sort of software translator; it could probably be done using an Arduino but the effrot required could range from trivial to heavy lifting.

Neil

Thanks Neil and Dave for your reply’s, as you say it’s not an easy fix and it may pay me to replace the power supply and controller boards but where do I stop with old stepper motors as well?

Len.

From a newbie perspective a major issue is the pace of technological change. Generally the things you find on line are relatively old (in electronics terms) and describe what could be affordably done then without unreasonable amounts of engineering. Almost invariable there are limitations in what the results can do and how well it works. But for the time such were more than acceptable.

The original BBC system is seriously limited from modern day viewpoints but it worked. In the context of its time where the nearest "low cost(?)" equivalent might well have been something like a Bridgeport EziTrack, early Haas or one of the relatively expensive small "desktop size" systems it was wonderful. Especially for the money. Not that it was pocket money cheap. More like small car territory!

But a stepper motor is a stepper motor, a limit switch is a limit switch and modern electronics are both powerful and relatively cheap so the dump all the electronics and start over approach has gotten more attractive. I'm rather impressed by the Granite devices blurb **LINK** which implies that you can pretty much wire up a system and have it just work with none of the lost steps and similar issues that plague older approaches if you mess up the set-up. Older affordable systems generally don't have nice easy to follow graphical set up screens, far too expensive then, which really doesn't help the novice.

I'm sure smothstepper and similar buffering interfaces can do the job just as well but how much extra set-up is involved and how tricky is doing the mix an match to the drives on your bench. As an older guy (67 come July) I'd definitely favour the "works out of the box" solution when someone else has done the hard work for me unless its prohibitively expensive. Young Clive would take anything on DIY and spent far too much time for, all too often, working but not really well enough results. But he couldn't afford the good stuff then!

Worth remembering that Mach is very old technology too. Probably should look for something more up to date.

Or maybe the complete Chinese control boxes would be better approach altogether. The late (Sir) John Stevenson was impressed by these so they'd have to be a least pretty darn good in practice. Some discussion on earlier threads.

Clive

Hi Len

Does your cable plug into a board like this?

From memory(very dangerous). I removed the board and made my own interface PCB which then plugged into a generic 5 way break out board which then went to mach3 through a parallel cable.

Cheers Michael.

Does your lathe have a thread cutting capability? If so, you'll need a control system with that too.

LinuxCNC, Centroid Acorn and PlanetCNC have good thread cutting implementations, many others are only geared towards milling machines & routers, but not lathes.

I have PlanetCNC fitted on my Denford lathe and it was quite straightforward to retro-fit. Have a look at the manual for the 4-axis board (which I have), in particular, the wiring examples towards the end of the document.

Martin.

Thanks everyone for your help and yes Graham I’ve had to replace the two capacitors in the Gemini controller several years ago, after a loud bang and smoke I thought that sounds expensive, but thankfully just replacement parts and a bit of soldering.

So perhaps I will work out stepper motor sizes and go from there, and after getting it going again yesterday in manual mode the motor starts and the variable speed works but only one way for some reason, the reversing relay is not working, more to have a look at, so any diagrams would be helpful.

Len.

Hi Len, Please send me an email to "GrahamNOspam@Karel.uk.net" and I'll reply with the schematics I have. If anyone else wants them please feel free to email also.

All the best

Graham

Hi just an update I’ve just ordered a pair of stepper drivers and motors and a power supply, I see from the circuit diagram that the original steppers are an 8 wire configuration with 4wires from the stepper driver board and the other 4 wires paired and then supplied with a 24v through six resistors three for each phase.

so rather than risk blowing up my drivers I will fit the new ones, they are 4wire bipolar, the only thing that concerns me is that once I remove the stepper driver board and the microprocessor board I see that the spindle indexing and the forward and reverse for the spindle will no longer work, is there an off the shelf controller for this?

Thank you Graham for the board diagram but I’m not as I said an electronic wiz kid and building a board from scratch is beyond me so would like advice from you guys.

Len.

Edited By Leonard Newton 1 on 12/04/2020 18:33:09

I thought I would give you all an update on my Boxford 125TCL I actually looked through loads of specifications on motors, drivers and power supplies and thought I would look on eBay and found an easy option, a bundle with two stepper motors, drivers and a power supply, I already have a Mach3 breakout board.

They were Nema 23 type with a 270oz rating the higher powered ones had a longer body length particularly for the x axis, I removed the old microprocessor and stepper boards inc a large capacitor and the associated wiring, fitted the replacement motors etc and after a lot of fiddling about got it to run on Mach3 demo. I have wired up the z stop micro switch n/c so there is no chance of running the tool into the chuck, I’m using Mach3 Turn but I don’t seem to be able to set up the soft limits, any help would be appreciated.

The motors seem to have plenty of power although I haven’t started to cut anything yet, with the help of Graham with his advice and a wiring diagram I’m hopefully wiring in a double relay to enable the motor to run forward and reverse, I’m still waiting for this item at the moment. This has been an interesting project for me as a novice and great to get the steppers controlled by a computer, I know I haven’t finished yet but thanks to you all for your help and encouragement.

Len.

Hi Martin the answers to your questions are the Boxford has a z switch fitted as standard Which I have wired to my breakout board, there are switches everywhere on this machine two on the Perspex cover and hinges the rear and side covers etc, I think because it was designed as an educational machine they went over board to stop little fingers fiddling.

I have not set x and z yet but it seems that you don’t need limit switches to set up soft limits as long as the machine is not moved manually when the Mach3 program is switched off, I have tried setting the the z axis to – and the x axis to + so the chuck end and up as my zeros and then putting in the travel for each axis as 100.00mm but I keep getting out of limits, there seems to be a difference between Mach3 lathe and Mach3 turn, which is best? as the Mach3 turn doesn’t seem to have a soft limit button and the Mach3 lathe uses the page up and page down keys instead of the up and down arrows, if you set one up the axis go a different way on the other, it’s probably me but do you initially set up the lathe or the turn versions?

And I haven’t got the spindle moving yet.

Len.